The present invention relates generally to an internal combustion engine, and particularly to a fuel injected engine designed to facilitate cold starting of the engine.
Internal combustion engines generally have one or more cylinders through which one or more pistons move in a reciprocating manner. Each piston is connected to a crankshaft by a connecting rod able to deliver force from the piston to the crankshaft to rotate the crankshaft. Power to drive the piston is provided by igniting a fuel-air mixture disposed in the cylinder on a side of the piston opposite the connecting rod. The fuel-air mixture is ignited by some type of ignition device, such as a spark plug.
Internal combustion engines, such as two-stroke engines, can be difficult to start when cold. This is particularly true when less volatile fuel types, such as kerosene, are used to power the engine. When the engine is cold, the fuel tends to atomize less, resulting in difficult starts. Once the engine is running, the environment into which fuel is introduced is both hotter and more turbulent for better fuel/air mixing and, consequently, better combustion.
During a cold start, however, it would be advantageous to have a system able to facilitate the mixing of fuel and air for more consistent starting of the engine.
According to one aspect of the present invention, a strategy is provided for facilitating cold starting of an internal combustion engine, e.g., a two-stroke or direct injection four-stroke engine. The strategy comprises delivering a fuel into a combustion chamber of a cylinder when the cylinder is cool, i.e., during a cold start. During this cold start, the fuel is delivered into the combustion chamber each time the piston approaches top dead center, preferably between 10 degrees and 0 degrees before top dead. center. The method also includes igniting the fuel with a spark before, during and/or after delivery of the fuel within the combustion chamber.
According to another aspect of the invention, a method is provided to facilitate cold starting of an outboard motor having an internal combustion engine in which a piston is disposed for reciprocable motion through a cylinder. The method includes locating the internal combustion engine in an outboard motor. The method also includes injecting a fuel into a combustion chamber of the engine approximately 10 degrees to 0 degrees before the piston reaches top dead center. The method further includes igniting the fuel to drive the piston.
According to another aspect of the present invention, an internal combustion engine system is provided. This system can be used, for example, in a marine application, e.g. a watercraft. The internal combustion engine system comprises a two-stroke engine having at least one cylinder and a piston disposed in the at least one cylinder. Additionally, a fuel injection system and an ignition system are controlled by an electronic control unit. The electronic control unit is configured such that during a cold start the electronic control unit causes the fuel injection system to inject a fuel into the at least one cylinder when the piston approaches top dead center.